Constructor in Java

  • It is a special kind of method which is used to initialize the object.
  • A block of codes same as the method.
  • It is called when an instance of the class is created. 


Types of Constructor

  1. Default constructor     (no-argument)
  2. Parameterized constructor    (argument)

Default Constructor

It doesn't have any parameter.

Example :  

class Student
{  
//creating a default constructor  
Student ()
{
System.out.println("Student is created");
}  
//main method  
public static void main(String args[]){  
//calling a default constructor  
Student s=new Student ();  
}  
}


Output :

Student is created

Parameterized Constructor

It has a specific number of parameters.

Example :

class Student
{  
    String name;  
    int age;  
    //creating one arg constructor  
    Student(String n)
    { 
    name = n;  
    }  
    //creating two arg constructor  
    Student(String n)
    {   
    name = n;  
    age=a;  
    }  
    void display()
  {
    System.out.println(name+" "+age);
  }  
    public static void main(String args[]){  
    Student s1 = new Student("Karan");  
    Student s2 = new Student("Aryan",15);  
    s1.display();  
    s2.display();  
   }  
}  


Output :

Karan 0
Aryan 15